Background checks for firearms purchases spiked after the December 14 mass shooting at a school in Newtown, Connecticut, new data from the FBI showed on Monday.

Background checks for firearms purchases spiked after the December 14 mass shooting at a school in Newtown, Connecticut, new data from the FBI showed on Monday.

According to data from the Federal Bureau of Investigation's National Instant Criminal Background Check System (NICS), nine of the top 10 days for firearms checks from November 30, 1998, to January 27, 2013, including December 14, 2012, occurred since Adam Lanza killed 20 children and six adults at Sandy Hook Elementary School and then shot and killed himself.

Lanza also killed his mother before the school massacre. His use of an AR 15 assault-type rifle and high-capacity ammunition magazines have been at the heart of the contentious debate over gun control.

The NICS is a nationwide system for checking criminal records, developed by the FBI with the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) and local and state law enforcement agencies. The system is run by the FBI.

According to the FBI data, the leading six days for background checks before the sale of firearms occurred after December 14, 2012. The top five weeks for background checks were the week of the massacre and afterward.

Since November 30, 1998, the top day for background checks before gun sales was December 21, 2012, a week after the massacre. Checks that day numbered 177,170.

The top week since November 30, 1998, was December 17 to December 23, 2012, when 953,613 background checks were requested.

Gun control advocates argue that civilians do not need to own assault weapons and high-capacity magazines. Gun rights supporters argue that efforts to ban assault weapons are an attack on the second amendment right of the U.S. constitution, which addresses the right to bear arms.